Many fluid systems use articulating vanes to control the direction and flow rate of the fluid within the system. Gas turbine engines are one example of such a fluid system. The typical gas turbine engine controls the flow rate of the air moving through engine with an array of vanes located in the inlet or outlet of the engine, or in a duct within the engine. As the vanes are articulated, the vanes are subjected to fluid impingent on the surface of the vane which imparts an aerodynamic force on the vane. Traditional vanes are designed to articulate about an axis intersecting the vane in a location such that the aerodynamic forces acting on each side of the axis is balanced in order to minimize the net aerodynamic moment on the vane, thereby “self-balancing” the vane. However, the complexity of fluid flow over a range of angles of attack frustrates the design of these self-balanced vanes. A given vane may be incapable of self-balancing over a range of angles of attack since the aerodynamic forces on the leading and trailing surface areas of the vane may vary differently from one another.
Additionally, the array of vanes within a typical gas turbine engine also articulate uniformly in a single direction. Since each vane will not be self-balanced over a range of angles of attack, the moments exerted on the array of vanes will lead to an accumulation of resisting forces on the vane actuator. Typical vane actuation systems and actuators are sized based on these accumulating forces. In turn, the size and weight of the envelope surrounding the engine duct is affected by the size of the actuator.
The present application discloses one or more of the features recited in the appended claims and/or the following features which, alone or in any combination, may comprise patentable subject matter.
The present disclosure is directed to a system which addresses the deficiencies of accumulating loads caused by the shortcomings of self-balanced vanes.
According to an aspect of the present disclosure, a system is provided for directing the flow of a fluid and controlling the rate of flow of the fluid. The system comprises a channel for directing the flow of the fluid; at least a pair of articulating vanes positioned within the channel for controlling the flow rate of the fluid within the channel, each of the vanes comprising a pair of lateral major surfaces forming a leading edge and a trailing edge of the vane, and an axis of articulation intersecting the vane at a point spaced from the aerodynamic center of the vane; and a linkage between the vanes coupling the articulation of each of the vanes to the other of the vanes, wherein each vane imparts a force on the linkage when the relative angle of attack is greater than zero, wherein the force imparted on the linkage by one of the vanes is at least partially cancelled by the force imparted on the linkage by the other of the vanes during the articulation of the vanes.
According to another aspect of the present disclosure, a system is provided for directing the flow of a fluid in a turbofan jet engine and controlling the rate of flow of the fluid. The system comprises a duct for directing the flow of the fluid along a centerline axis of the engine; an array of articulating vanes positioned circumferentially around the centerline axis within the duct for directing and controlling the flow of the fluid within the duct, each of the vanes comprising a pair of lateral major surfaces forming a leading edge and trailing edge of the vane, a stem protruding through the duct, and an axis of articulation intersecting the vane at a point spaced from the aerodynamic center of the vane; and a circumferential actuation ring positioned outside the duct, the actuation ring being operably coupled to the stern of each of the vanes to couple the articulation of each vane about its axis of articulation, wherein each vane imparts a force on the actuation ring when the relative angle of attack is greater than zero, wherein the force imparted on the actuation ring by one of the vanes is at least partially cancelled by the force imparted on the actuation ring by at least one other of the vanes during articulation of the vanes.
While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the present disclosure is not intended to be limited to the particular forms disclosed. Rather, the present disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.